Perhaps you should try some spelling variations:
dong thuong » cong thuong, dong thong, dung thuong
thieu sach » chieu sach, thien hach, theo sach
thuong dan » huong dan, thuong han, thuong dam
hieu cach » hieu cac, chieu sach, hieu ca
tuan dong » tuan duong, quan dong, luan dong
dan khan » dan khanh, dan chan, dan than
khan cap » khan ap, than cap, khoan cam

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((thieu sach) OR (hieu cach)) - ((thanh tung) or (thanh cong)) tuan dong thuong dan khan cap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu sach) OR (hieu cach)) - ((thanh tung) OR (thanh cong)) tuan dong thuong dan khan cap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu sach) OR (hieu cach)) - ((thanh tung) or (thanh cong)) tuan dong thuong dan khan cap".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sach) OR (hieu cach)) - ((thanh tung) or (thanh cong)) tuan dong thuong dan khan cap*.